Pneumatic jack



Fume 3, 1924; 1,496,418

S. KA'HN- PNEUMATIC JACK Filed May 14 1923 j ATTORNEY Patented June 3, 1924.

PATENT FF'ICE.

SAMUEL KAHN, LONG ISLAND CITY, NEW YORK.

PNEUMATIC JACK.

Application filed. May 1c, 1923. Serial No. 638,689.

To all whom it may concern:

Be it known that I, SAMUEL KAHN, a citizen of the United States, residing at Long Island Cit in the county of Queens and State of ew York, have invented certain new, and useful Improvements in Pneumatic Jacks, of which the following is a specification.

This invention relates to hoisting devices and has particular reference to acks for lifting, and holding more or less temporarily, heavy loads.

Among the objects of the invention is to provide a lifting jack, the power for which is derived from a fluid under pressure from any suitable source, the fluid preferably being in the nature of an expansible gas, although it will of course be understood that the body of the jack is adaptable for use in 2o connection with any fluid under pressure.

Another-object of the. invention is taprovide a pneumatic jack including .a piston having a self sealing gasket, the sealing efficacy of Which is directly proportional to and operates as a result of the degree of pressure applied to it. 1

A still further obj ect of the invention is to provide a fluid operated piston comprising relatively movable'parts adjustable tower and from each other as a result of relative rotation between said parts.

Another object-of the invention is to provide a fluid operated hoist with positive means for holding the plunger or shank portion thereof elevated, and with means for automatically releasing the positive holding means as a result of the. disconnection of the fluid supply means. 1

,With the foregoing and other objects in view the invention consists in the arrangement and combination of parts hereinafter described and claimed, and while the invention is not restricted to the exact details of construction disclosed or suggested herein, still for the purpose of. illustrating a practical embodiment thereof reference is had to the accompanying drawings, in which like reference characters designate the same parts in the several views, and in which- Figure l isa vertical sectional view show- Fitted slidably within the flanged end of the ing a preferred embodiment of the main portions of my improvement.

Fig. 2 is a partial plan view and partial section on the line 2-2 of Fig. 1.

Fig. 3 is adetail showing a changed position of the piston and the compression of the gasket underhigh pressure and resistance.

Referring now more specifically to the drawings I show my lifting jack as comprising a cylinder 10 formed with or secured to in any suitable manner a base 11 to which the cylinder is secured and having a valve extension 12 at one side with a releasing valve 13. A port 14: leads from the bottom of the cylinder. Near its edge said base 11 is provided with a pin or stud 15 extending upward slightly above the top surface thereof close to the side wall of the cylinder. At its upper end the cylinder is fitted with a removable cap 16 having an outer flange 17 secured suitably upon the upper end-of the cylinder. This-cap has a central guide hole 18 formed-.therethrough.

19 indicates a pipe or tube which will be understood as serving no only as a means for introducing the pressure fluid into the cylinder, as soon to be described, but also as a handle for manipulating the jack into and out of position,- as for example, beneath the axle of an automobile or the like. 20 represents a coupling member fixed to thepipe' 19 and having swinging or pivotal connection with a nipple section 21, having a port 22 communicating with the port 14. The pipe 19 acts as a lever so that when it is swung downward a lug 19 opens the valve 13.

One of the principal parts of the improvement is the piston having a body portion 25 fitted for easy sliding movement within the cylinder 10. The lower end of this piston body is provided with an inwardly directed flange 26, and adjacent to this flanged portion of the body is provided a pin 27 extending horizontally of and beyond the flange.

body is a cup shaped pressure member 28 whose upper edge, isoutwardly flared to overlap the flange 26 and whereby the cup is limited in its downward movement relative to the body. A notch 29 is provided on one side of the cup to accommodate the pin 27. By this means the cup and body are held from relative rotation while the cup may move upward relatively. The bottom of the cup communicates directly with the passage way 14 of the base for the pressure fluid admitted through the pipe 19 past a check valve 13'. 30 indicates a pressure ring sur rounding and externally threaded upon the lower end of the cup. This ring is provided alon its bottom surface with a series of note es 31, any one of which may receive the ppper' end of the stud 15 whereby the ring is eld from rotation when at the bottom of the cylinder. The parts are so designed that the ring 30 is spaced suihciently from the lower end of the body 25 to accommodate a compressible gasket 32 of relatively soft rubber or its equivalent, the main purpose of which is to seal the space between the piston and the cylinder wall.

The plunger portion of the device comprises a shank or pedestal 33 of generally round structure but provided with a succession of annular notches 34 between its ends. The upper bounding surface of each notch is concaved as indicated at 34'. The lower end of the pedestal is reduced, forming a shank 35 fitted through the center of the top 36 of the piston body and locked in such position tightly by means of a lock nut 37 or its equivalent. The top 36 is separable, as a shop expedient, from the body 25, the cup 28 being inserted before the body and its top are assembled. At the upper end of the pedestal is swiveled a head 38 for receiving directly the load to be lifted.

Pivoted in any suitable manner at the cap 16 is a pawl 39 shown in the nature of a bell crank lever, the shorter arm or point of which is rounded at 40 for co-operation with the several notches 34, the pawl being urged for such cooperation by any suitably arranged spring 41. The pawl includes a pair of trunnions 42 journaled in bearings 43 for movement around a horizontal axis. The pawl may be released from its holding position by any convenient means, but to this end I provide a connector 44 between the outer longer end of the bell crank and a stud 45 extending laterally from'or otherwise loosely jointed to the handle pipe 19 so that when the handle pipe is swung as indicated the connector will be drawn downward, causing the pawl to be withdrawn from its holding position, and then inturn the valve 13 will be opened more or less to afi'ord easy and direct control by the operator of the lowering of the load. It will be noted that the form of the surface 34 with which the point 40 of the pawl co-operates enables me to release the pawl while the device is sustaining its load. Usually in the operation of a lifting jack the load is required to be lifted as a preliminary to its being lowered. The connector 44 is shown in the nature of a hook or with a long loop, permittingfree oscillation of the pawl while the pedestal is being lifted, and yet the connector may be readily disconnected from the pawl when the parts are disassembled or folded for transportation or storage.

With the parts constructed as set forth the pedestal will be inserted through the guide hole 18 of the cap 16, and with the main parts of the piston assembled as above described, the gasket 32 will be passed around the cup 28 and the pressure ring 30 will be screwed into place lightly, exerting slight pressure upon the gasket or just enough to provide enough contact between it and the cylinder wall to furnish the automatic compressive action. The piston will now he slipped into place through the open upper end of the cylinder, bringing the ring 30 down to the bottom of the cylinder, and the cap 16 will then be applied to the cylinder. To tighten the gasket to produce suiiicient tension or contact between it and the cylinder either initially or after any subsequent period of use, the operator simply rotates the pedestal either by hand or a tool applied to the upper end thereof, causing the rotation of the body 25 and the cup 28. The ring. 30 being held from rotation at such time, the gasket 32 will be compressed until the outer surface thereof bulges sufiiciently for the purpose indicated. Ordinarily, however, it will be understood that the degree of compression of the gasket is relatively slight in so far as the rotation of the tightening action of the ring 30 itself is concerned. After adjustment as just described the cup 28 and ring 30 act as a unit, and so when the fluid pressure is applied to the bottom of the cup such pressure will act directly to compress the gasket 32 and cause it to bulge suiiiciently forcibly against the wall of the cylinder to prevent leakage of the pressure fluid past the piston. The greater the pressure that is applied to the pressure cup the greater will be the compression of the gasket and the tighter will be the seal. When, however, the fluid pressure is relieved from the bottom of the piston the gasket tends to resume its normal form, making it easy for the piston to slide along the cylinder.

1 claim:

1. A pneumatic jack comprising a cylinder, a piston movable along the cylinder, load lifting means connected to the piston and operated thereby, means to admit a pressure fluid into the cylinder for moving the piston, said admission means including a relatively movable tubular member, a locking member co-operating with the load lifting means, and connections between the relatively movable anemia member just described and said locking means for releasing the same when the relatively movable member is moved.

2. In a pneumatic jack, the combination of a cylinder, means to introduce a pressure fluid into the cylinder, said means including two pipe sections, one movable relatively to the other, a piston movable within the cylinincluding a rotatable part, anexpansible ring, and a non-rotatable member co-acting therewith, and a power transmitting member connected to the piston and constituting a means for rotating the rotatable part from the pistonthereof While in the cylinder.

4. A lifting jack of the nature set forth in claim 3 in which the power transmitting member is a rigid pedestal provided with a series of annular notches, and a locking dog carried by the cylinder and co-operating with any one of said notches irrespective of the rotation of the pedestal.

5. In a pneumatic jack, the combination of a cylinder, meansto admit a pressure fluid thereinto, a piston slidable along the cylinder under the influence of said ressure fluid, said piston comprising a b0 y, a pressure member including a ring co-operating therewith and slidable lengthwise relatively thereof, and an expansion member.

adjacent to the inner surface of the cylinder and locatedbetween said, pressure ring and said body, means operative externally of the piston to initially vary the space between said body and said pressure ring, said expansion member being expanded as a result of the relative endwise movement of the pressure member with respect to the body, and means to transmit the power;

6. In a device as set' forth, a cylinder, means to admit a power fluid thereinto, a

piston slidable within the cylinder under the force of said fluid, said piston com rising a rotatable part and a non-rotata le' art spaced from each other, and also inclu ing a gasket inthespace between said two parts for making tight connection between the piston and the cylinder, the piston including also a member co-acting with the non-' rotatable part to cause variation in said space when the rotatable part is rotated,

which the connector is to permit the free oscillation of the hold- 7 The combination with a piston comprising a body portion, a compression member slidable longitudinally of this body portion and comprising two parts relatively movable to each other, one of the parts being a ring, and a gasket between-the compression member ring and the body, of means to effect the relative'movement between the two parts of the compression member to vary initially the tightness of the gasket.

8. A structure as set, forth in claim 7 in which the compression member ring is 'held from rotation for initial adjustment, and means is provided to rotate the body.

9. In a lifting jack, a pedestal having a series of notches, means to elevate the pedestal, and a dog mounted in a relatively stationary position'and co-operating in suec'ession with said notches to automatically sustain the load elevated, said notches and dog being so constructed as to enable the dog to be readily withdrawn from holding position while the maximum load is upon the pedestal.

10. A jack as set forth in claim 9 in which the pedestal is of round form and.

the notches are annular.

11. The combination with a piston comprising a compression ring, a gasket adjacent thereto, and other structure co-operating with the gasket, the ring and other structure being relatively rotatable, of means to hold the ring from rotation, and

means to rotate the other structure for initial adjustment of the gasket.

-12. In a pneumatic pressure jack, the combination of a cylinder, a piston slidable therein, means including a movable member to admit pressure fluid into the cylinder, and a discharge valve communicating with the fluid admission means andcontrolled thereby. I

13. A jack as set forth in claim 12 in which the communication between the fluid admission means and said discharge valve is effected by a means allowing considerable free movement of the fluid admission means before said valve is operated.

14. A jack as set forth in claim 12 ineludingv load lifting means and positive means co-operating with the load lifting Ill means to hold the load elevated, andconnections between the last mentioned means and said movable member'for' withdrawing the holding means.

15. A jack as set forth in claim 14 in rovided with means ing means while the load is being lifted.

16. In a neumatic jack, the combination of a cylin er, a piston slidable therein,

means including a movable member to ad mit pressure fluid into the cylinder, a valve communicating with the fluid admission means to control the dischargeof the fluid and so constructed as to be opened by direct engagementby said movable member, a load lifting member connected to the piston, ositive means co-operating with the load 'fting member to hold the load elevated, and connections between the last mentioned w means and said movable member for withdrawing the holding meansand opening the valve to permitthe load to descend.

In testimony whereof I affix my signature.

SAMUEL N. 

